fix(label): (1) Use uniform label utils on pie label layout. (2) Fix the inconsistent behavior in pie label layout - (2.1) Previously calling `getBoundingRect` before textConfig applied (causing the result diff). (2.2) Previously adding extra margin for "auto text stroke" even if no auto text stroke added. Currently use https://github.com/ecomfe/zrender/pull/1134 to uniform the behavior.